Method for manufacturing crimped acrylonitrile filament yarn



0d. 21, 1969 KENZO KOSAKA ET AL, 3,473,317

METHOD FOR MANUFACTURING CRIMPED ACRYLONITRILE FILAMENT YARN Filed April 11, 1968 IOO lOOO lOg (TIME IN HOUR) m w m m M28 mo mmwz m/i nited States Patent 0 U5. Cl. 57-457 9 Claims ABSTRACT OF THE DISCLOSURE An improved method for manufacturing crimped acrylonitrile filament yarn by ejecting a hot, wet medium to filaments to be crimped just after they come out of a heater, imparting crimps to the filaments, taking up the crimped filament yarn onto a bobbin at a predetermined winding ratio and applying a heat set treatment upon the filament yarn after it is wound on the bobbin.

The acrylonitrile crimped filament yarn manufactured by the method of the invention is provided with crimps of excellent stabiilty, reduced thermal shrinkage and uniform afiinity to dye.

Dyeing of the filament yarn can be performed either simultaneously with the heat-set or after the heat set.

The present invention relates to an improved method for manufacturing crimped acrylonitrile filament yarn having superior qualities, by ejecting a hot, wet medium to filaments just after they come out of a heater, imparting crimps to the filaments, taking up the obtained crimped filament yarn onto a bobbin at a predetermined winding raito and applying a heat-set treatment upon the filament yarn after it is wound on the bobbin, thereby producing acrylonitrile crimped yarn having crimps of excellent stability and uniform affinity to dye.

The term winding ratio as used herein refers to a ratio in percent of the difference between the surface speed of a delivery roller and the surface speed of a take-up roller with respect to the surface speed of the delivery roller.

As is well known, the so-called false-twisting process is one of the popular methods for manufacturing crimped yarn of synthetic filaments such as nylon, polyethylene terephthalate and polypropylene. After being provided with potential crimps, the filament yarn is usually woven or knitted into textile clothes, subjected to a suitable crimp developing treatment and dyed according to the requirements of the end use.

However, in case of imparting crimps to acrylonitrile filaments, a method is generally recommended of carrying out the process while applying tension to the filaments in order to prevent lowering of the strength of the filaments due to heating. Consequently, the acrylonitrile crimped filament yarn obtained is provided with a rather high degree of thermal shrinkage which results in unfavourable problems in the subsequent steps.

There are two known methods for reducing the thermal shrinkage of the crimped filament yarn obtained. In the first method heat-set is applied to the yarn in the form of a skein while shrinking the yarn. However, it is very difficult to obtain the yarn in the form of a skein because of frequent filament of yarn breakage due to lower tenacity of acrylonitrile filaments when compared with other synthetic filaments such as polyamide, polyethylene terephthalate or polypropylene. Moreover, in the case of acrylonitrile filaments, a small fluctuation in the processing tension often results in a large fluctuation in crimp properties of the filament yarn obtained because of unstable thermal characteristics of acrylonitrile polymers. In the ice second method, heat-set is applied to the yarn in the form of a package. However, in this case, it is practically impossible to make the winding ratio of the yarn higher than the degree of thermal shrinkage of the yarn. Consequently, the yarn on the package is in a stretched condition throughout the heat-setting treatment, and this often results in loss of preferable soft hand of the yarn obtained which is peculiar to an acrylonitrile filament yarn.

Overfeeding of the yarn in the process for manufactur ing crimped filament yarn is performed within a region between the delivery roller and the take-up roller. However, it is difficult to realize high winding ratios exceeding 10% during overfeeding of the yarn in the conventional method on account of the fact that shrinkage of arylonitrile filament does not take place so quickly as in the case of polyamide, polyethylene terephthalate and polypropylene. This tendency becomes more marked as the processing speed of the filaments is increased, and, finally, the degree of thermal shrinkage becomes larger than the winding ratio at a processing speed of the filaments which is generally employed in the production of synthetic filament yarns. This delayed shrinkage of the filament yarn, which is characteristic of acrylonitrile fibers, often causes shrinkage of the filament yarn even after being wound onto a package. As a result, the hardness of the package is increased by this delayed shrinkage of the filament yarn and causes an uneven heat setting effect.

As mentioned above, the dimensional stability of acrylonitrile filament is very low when an external force is loaded on the filament in a hot, wet condition. Therefore, crimps imparted to the filament by the conventional method are liable to be lost considerably when a textile product made of such crimped filament yarns is subjected to dyeing. In order to avoid this problem, polymer solution dyeing or yarn dyeing is generally employed for acrylonitrile fibers. However, in case of polymer solution dyeing, it is practically impossible to change colours without manual work whenever this is required because of the fact that it is necessary to pump the old spinning solution completely out of the spinning machine and clean the inside of the spinning machine prior to the introduction of a new spinning solution. On the other hand, in case of yarn dyeing, the above-described delayed shrinkage of the filament yarn wound on a package causes uneven dyeing of the yarn. Moreover, special caution must be taken so as to prevent contamination of the dyed yarn during the following processes.

As is clearly understood from the foregoing description, it is difiicult to carry out mass production of crimped acrylonitrile filament yarns at a low production cost in spite of the fact that they have been preferred because of their excellent hand. A further drawback of the conventional crimped acrylonitrile filament yarn is poor dimensional stability in a hot, wet state.

After repeated studies for crimping acrylonitrile filaments, the inventor of the present invention arrived at the conclusion that the above-described drawbacks of conventional acrylonitrile filament yarn is due to characteristics in thermal shrinkage of acrylonitrile filaments and that the thermal shrinkage of acrylonitrile filaments is considerably affected by the moisture content of the filament to be crimped, that is, the higher the moisture content of the filament just after coming out of the heater positioned before a twisting zone, the larger is the thermal shrinkage of the filament in the twisting Zone and the larger is the development of crimps of the filament yarn obtained.

A principal object of the present invention is to provide an improved method for manufacturing crimped acrylonitrile filament yarn having crimps of excellent stability.

Another object of the present invention is to provide an improved method for manufacturing crimped acrylonitrile filament yarn which can be subjected to piece dyeing without any processing trouble.

A further object of the present invention is to provide an improved method for manufacturing crimped acrylonitrile filament yarn, textile products made therefrom being provided with excellent dimensional stability.

A still further object of the present invention is to provide a novel method for manufacturing crimped acrylonitrile filament yarn on a simple apparatus and at a low production cost.

In accordance with above-described objects of the invention, the method of the present invention comprises ejecting a hot, wet medium having a relative humidity from 40% to 90% to filaments just after they come out of a heater, imparting crimps to the filaments, taking up the crimped filament yarn onto a bobbin at a winding ratio higher than and applying heat-set treatment upon the filament yarn after it is wound on the bobbin.

In the above-described procedure, the filament yarn can also be wound onto a cheese or a cone instead of a bobbin, and the term bobbin as used herein covers a bobbin, cheese and cone. The heat-set treatment can be performed in steam or heated liquid bath. In the latter case, dyeing can be performed simultaneously with the heat-set treatment.

Acrylonitrile filaments used in the present invention are characterized by containing from 50 to 100% by weight of acrylonitriles and being substantially provided with properties characteristic of acrylonitrile fibers.

As the hot, wet medium to be ejected to the filaments, either heated wet air or steam can be favourably used in the present invention. Ejection of the hot, wet medium should be performed while the temperature of the filaments is maintained as high as possible, in other words, at a position as close to the outlet of the heater as possible. This is one of the important keys for carrying out the method of the present invention with good results because of the fact that it is difiicult to expect good results by the ejection of the hot, wet medium in case the temperature of the filaments to be crimped is lower than 100 C. In case steam is used in the present invention, lowering of the temperature of the filaments is not as great as in case of heated, wet air. On the other hand, in case heated, wet air is used in the present invention, dew formation on the surface of the filaments does not take place and properties of the crimped filament yarn obtained are not affected with the ejection rate and temperature of the air.

As to the temperature and relative humidity of the hot, wet medium ejected to the filaments in the present invention, a temperature from 85 to 110 C. and a relative humidity from 80 to 90% are required in case of steam while a temperature from to 100 C. and a relative humidity from 40 to 90% are required in case of heated, wet air. In any case, it is necessary to eject a hot, wet medium having a relative humidity from 40 to 90% to the filaments just after they come out of the heater.

Increase in tension applied upon the filaments caused by this ejection is only a few grams while increase in the tension caused by cooling which is performed for example by oiling the filaments is about 10 grams. Consequently, no alteration of the crimping conditions is required when using this ejection. From this fact, it is seen that the improvement in crimp recovery of the filament yarn obtained is not dependent upon cooling, but upon wetting the filaments.

From the point of view of the object of the present invention, of reducing the thermal shrinkage of the filament yarn and heat setting the filament yarn without destroying the crimped configuration thereof, it is desirable to use steam as the hot wet medium to be ejected to the filaments. However, from the view point of dyeability and ease of control of the degree of crimps, it is desirable to eject heated wet air to the filaments and thereafter to apply heat-set upon the crimped filament yarn wound on a bobbin within a heat-setting apparatus having uniform temperature distribution. Instead of applying heat-set in this manner, dyeing the yarn as it is wound on a bobbin or a cheese at high dyeing temperatures is also recommended in order to reduce the thermal shrinkage of the filament yarn obtained. In this case, simplification of the manufacturing process can be attained by the combination of heat setting and dyeing.

It is also possible to dye the yarn after it has been subjected to heat setting with steam in the form of a bobbin. In this case, the temperature of the steam should be maintained between 105 .and 130 C. and the relative humidity of the steam should be maintained between and 130%.

Further features and advantages of the present invention will be apparent from the ensuing description, reference being made to the accompanying drawing in which;

FIG. 1 is a graphical drawing showing the time functional change of the hardness of a cone of conventional crimped acrylonitrile filament yarn,

FIG. 2 is a schematic side view of an embodiment of the process for carrying out the method of the present invention.

Referring to FIG. 1, the time-functional change of the hardness of a cone of crimped acrylonitrile filament yarn is shown. In the drawing, the hardness of the cone is taken on the ordinate and the time in hours after the yarn is wound on the cone is taken on the abscissa on a logarithmic scale. The hardness of the cone was measured by using a cone hardness meter made by Nakaasa Sokki Co., Ltd, and the value of 0 corresponds to the softest condition of the cone while the value of corresponds to the hardest condition of the cone.

An embodiment of the process for carrying out the method of the present is shown in FIG. 2, wherein acrylonitrile filaments 2 are taken from a bobbin 1, led to a pair of feed rollers 4a and 4b through a tension controller 3, heated by a heater 6 positioned between the feed rollers 4a, 4b and a false-twist spindle 5, exposed to a hot, wet medium ejected as shown by the arrow in the drawing from a nozzle 7 disposed close to the outlet portion of the heater 6, twisted and untwisted by the false-twist spindle 5, led to a delivery roller 8 and taken up onto a package 10 by a take-up roller 9.

The following examples are illustrative of the present invention but are not to be construed as limiting the same. The terms used in the examples are measured and defined as follows.

1. Percent thermal shrinkage The distance 1 between two marked points of a crimped filament yarn was measured while loading 0.05 g./denier of weight to the yarn. Next, the yarn was unloaded, heated in boiling water for 20 minutes in a freely shrinkable condition and dried. Again the distance 1 between the two originally marked points was measured while loading 0.05 g./denier of weight to the yarn. The value of percent thermal shrinkage is given by 2. Percent crimp and percent crimp recovery 20 winds of skein were left for 24 hours at room conditions to allow free shrinkage. Then the skein was heated at 60 C. for 20 minutes in a dry condition for the purpose of bulking. The length 1 of the skein thus prepared was measured while loading 1 mg./ denier of weight to the skein for 1 minute, and next the length 1 of the skein was measured while loading 0.1 g./denier of weight to the skein for 1 minute. 2 minutes after unloading the weight, the skein was again loaded with 1 mg./denier of weight and the length 1 of the skein under the loaded condition was measured. In order to obtain the average, measurements were repeated times for each length of the skein, and the values were obtained as follows.

position close to the outlet of the heater, up to even 45% winding ratio was possible as shown in the following table and the hardness of the package was not increased with a winding ratio of higher than 10%. Moreover, both of Percent i 100 5 above-described steam setting and package dyeing could 1 be applied to the yarn without any trouble. Thermal 1 shrinkage of the yarn could be decreased considerably, Percent crimp recovery=ll 100 especially in case heated steam was used as the hot wet 0 medium.

TABLE 1 Heated wet air to be ejected Relative Maximum Thermal Uneven- Percent Temperhumidity Ejection winding shrinkage ness of crimp ature in in rate in ratio in of in dyeing contraction 0 percent ce./min. percent percent efiect in percent No. of sample 0 200 8 10.3 X 38.6 40 200 18 8.6 O 42.5 60 200 6.5 O 44.3 80 200 20 7.3 O 43.6 60 200 20 8. 2 O 44. 5 60 200 20 8.0 O 43.2 90 Little 16 2.3 A 41. 2

EXAMPLE 1 Leacril bright filaments (200 denier/80 filaments), which were manufactured by the ACSA in Italy, were subjected to false-twisting under the following conditions. (1) False-twisting machine A CS-9 false-twisting machine made by Ernest Scragg Co. in England. (2) Rotating speed of a falsetwisting spindle u 150,000 rpm. (3) Processing temperature 190 C. (4) Number of twists imparted to the filaments 1,750 twists/meter (S- twists). (5) Feeding ratio 8%.

When a hot, wet medium was not ejected, in other words when the conventional method was used, a winding ratio of only up to 10% was attained and it was difiicult to wind the crimped filament yarn on the package in a stable condition without missing traverse of the yarn in case the winding ratio exceeded 8%. The thermal shrinkage of the yarn obtained in boiling water was 10%. After applying steam set on the package at 120 C., the yarn positioned in the core portion of the package was provided with little crimp. When the yarn was dyed in the form of a package in the above-described dyeing condition, it was confirmed that there was a distinct difference in colours between the core portion and the outer portion of the package.

On the contrary, when the filaments were exposed to heated wet air or steam of 100 C. ejected obliquely with respect to the passage of the filaments from a nozzle at a In the table, the symbol X represents considerable unevenness of dyeing, the symbol A represents slight unevenness of dyeing and the symbol 0 represents no unevenness of dyeing. In case of sample No. 1 or no ejection of hot wet air, crimps of the yarn were lost during dyeing. Consequently, textile products made of this type of filament yarns were not different from those made of the conventional filament yarns. However, in case of textile products made of yarns manufactured by steaming at C. to 130 C. or cheese dyeing the crimped filament yarns of samples No. 2 to No. 7, were provided with good hand and excellent bulkiness which were not eliminated even by dyeing or applying wet finishing treatment upon the products.

EXAMPLE 2 The same filaments as those in Example 1 were fed to the same process as that in Example 1 with the only exception that hot wet medium was not ejected to the yarn. The hardness of the surface of a package of 400 g. obtained by taking up the crimped filament yarn at a Winding ratio of 8% increases gradually with time as shown in FIG. 1. When the yarn on the package was rewound into a cone, it was found that the end portion of the yarn, which corresponds to a weight 'of the last 100 g., was provided with a hardness of 45 and indicated a large difference in the degree of crimps from that of the beginning portion.

A knitted cloth, which was made by using the yarn obtained with an interlock rib knitting machine (16 gauge, 381 mm. dia., 732 ends), contained numerous thick and thin places along the filling direction. Besides, a large amount of deformation of the construction of the cloth was caused by dyeing. Consequently, the cloth is not suitable for textile products.

However, when wet air of 38 C. having a relative humidity of 65% was ejected to the filaments, the hardness of the surface of the package obtained by taking up the crimped filament yarn at a Winding ratio of 20% was 16 and this hardness increased very little even after being left for 24 hours. Then the crimps of the yarn were steam-set by using a steam setter at C. for 20 min utes, rewound onto a cone and knitted into a cloth using the above-described interlock rib knitting machine.

This knitted cloth was provided with a high degree of bulkiness and little deformation in the construction of the cloth due to dyeing was observed.

EXAMPLE 3 The same filaments as that in Example 1 were processed under the following conditions.

7 (1) False-twisting machine .A CS-9 falsetwisting machine made by Ernest Seragg Co. in England. (2) Rotating speed of the false-twisting spindle 160,000 rpm. (3) Processing temperature 210 C. (4) Number of twists imparted to the filaments 1,750 twists/meter. (5) Feeding ratio (6) Winding ratio (7) Ejected medium Steam.

Temperature 100 C. Ejection rate Very low.

The crimped filament yarn obtained was provided with crimp percent of 46.7, crimp recovery percent of 88.2 and 2.8% shrinkage in boiling water. An interlock rib fabric made of this yarn was dyed and finished under the following conditions.

( 1) Scouring:

Scoarol #900, 0.3 cc./l., 70 C. x min. (2) Dyeing:

(A) Dyestuffs Diacelliton fast pink B, 0.05% O.W.F. Blankophor DCB, 0.3% O.W.F. (B) Assistants- Dispersing agent, 0.7 cc./l. Acetic acid, 0.2 cc./l. Liquor ratio, 1:150 (C) Processing conditions-- Temperature, 100 C. Time, 60 min. (3) Washing:

Scoarol #900, 0.3 cc./l., 60 C. X 20 min.

After the treatment, the knitted cloth was provided with uniform color efifect, excellent bulkiness and comfortable soft hand. Moreover, this knitted cloth was provided with a high degree of dimensional stability which could withstand repeated washing and long use very well.

As stated in the foregoing description, a hot, wet medium having a relative humidity from to 90% is ejected to the filaments just after they come out of the heater, whereby thermal shrinkage and development of crimps take place within the twisting zone, resulting in less thermal shrinkage of the crimped filament yarn obtained. Next, the yarn is taken up onto a package at a winding ratio higher than 10% and subjected to steam-set in the form of the package, whereby loss of the crimps of the yarn is effectively prevented and a high degree of dimensional stability of the yarn is obtained. Furthermore, by applying heat-set upon the crimped filament yarn as it is wound onto a bobbin, cheese or cone simultaneously with dyeing, it is also possible to obtain a dyed crimped filament yarn having uniform color and high degree of dimensional stability.

While the invention has been described in conjunction with certain embodiments thereof, it is to be understood that various modifications and changes may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A method for manufacturing crimped acrylonitrile filament yarn characterized by ejecting a hot, wet medium having a relative humidity from 40% to 90% to filaments to be crimped at a position close to the outlet portion of a heater, imparting crimps to the filaments, taking up the crimped filament yarn onto a bobbin at a winding ratio higher than 10% and applying heat-set treatment upon said filament yarn after it is wound on said bobbin.

2. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, further characterized by dyeing said crimped filament yarn at a dyeing temperature from 110 to 130 C. simultaneously with said heatset treatment.

3. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, further characterized by dyeing said crimped filament yarn after said heatset treatment.

4. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, wherein the surface temperature of said heater is maintained between 150 and 240 C.

5. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, wherein said hot, wet medium is heated wet air maintained at a temperature from 20 to 100 C. and a relative humidity from to 90%.

6. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, wherein said hot, wet medium is steam maintained at a temperature from to 110 C. and a relative humidity from 80 to 7. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, wherein said filaments are maintained at a temperature between and 240 C. just after they come out of said heater.

8. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, wherein said winding ratio ranges between 10 and 45%.

9. A method for manufacturing crimped acrylonitrile filament yarn according to claim 1, further characterized by carrying out said heat-set by using steam maintained at a temperaturefrom to C. and relative humidity from 80 to 130%.

References Cited UNITED STATES PATENTS 2,962,857 12/1960 Wood et a1. 57-157 3,022,565 2/ 1962 Fitzgerald. 3,131,528 5/1964 Scragg 57157 XR 3,316,705 5/1967 Nava 57157 3,333,409 8/1967 Servage 57157 3,405,517 10/1968 Anahara et al 57-l57 FOREIGN PATENTS 1,081,189 8/ 1967 Great Britain. 1,098,545 1/ 1968 Great Britain.

MERVIN STEIN, Primary Examiner W. H. SCHROEDER, Assistant Examiner U.S. Cl. X.R. 57-35, 164 

